Well back when we were all modding civ3 many LOTR modds were made, but I beleave as I have not looked at all of them were based on the destruction of the Ring and defeating Sauron. Well what about what happened after Sauron was defeated, Aragon became King of Gondor, but I'm quiet sure that not every Orc, or Haradan were destroyed. In fact Tolken portrayed middle earth has before human history has we know it today, So why cant we view the human of middle earth in human term. What I mean what happens in today world if a very power force is suddently destroyed or removed, The underlings of such power break off form small bases of power of the own. Small kingdoms warrior tribes. We know from the text that there many thoundands of orcs, and other allies of sauron. Many of the people would have remained in middle earth and formed small groups of people bound together by similarities. The Gondorian kingdom would have been a weaked state when Aragon ascened the throne he would had to reorganize has kingdom rebuild his military and rebuild the internal infrastructure of gondor.
In fact this would be so for many of the Kingdoms of middleearth the people of Rohan will have just lost a king and have had its lands and farms destroyed.






Now has far as implementing the into a civ game

Look in Project and Mod Development. Click on the Arda Mod. It is a LotR mod that includes the four ages of middle earth.

http://upload.wikimedia.org/wikipedia/en/5/59/Middle-earth.jpg

See I want to make a Mod strictly on the fourth age of middle earth

The Arda mod is about ALL ages. if you want 4th age, join us...